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Thread: foam block under water heater?

  1. #31
    George the Plumber Gsalet's Avatar
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    I would just use foam myself but the plywood would keep legs from digging in from the top if it had legs. seamed to be a lot of energy about that <Grin>

  2. #32
    Service plumber. seattleplumber's Avatar
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    Default If it has feet, you don't need a pad...

    Quote Originally Posted by Dana View Post
    The feet have to extend to something structural, not resting on foam. If it's a flat-bottomed beast with mere dimpled sheet metal for feet it calls for building some. The last tank heater I owned was ca. 1982, had about 1.5-2" of clearance under it between some fairly substantial welded on feet, but I'm sure they're everything from dead-flat to fairly tall. I've seen a number of them with 2-3" structural rings beneath them for supporting the tank with some clearance,but I have no idea what/if there's a standard (I expect not.) Clearly it's easy to exceed 25psi many times over if it's a 3 metal feet or a stamped angle-iron ring holding up 600lbs. Looks like electric tanks often come with minimal clearance, whereas gas versions build in the necessary clearances for combusion air intake & burner heat issues:

    The whole point of the pad is to eliminate heat loss due to direct contact with the concrete floor. If the tank has feet that are more than just dimples in the sheet metal, a pad isn't necessary. Therefore, you wouldn't need to place a water heater with feet on a pad to begin with. That being said, if you try it the weight will sink the feet right through the pad. And if it's gas, it will melt the foam (seen it on an old style gas water heater).

  3. #33
    DIY Junior Member InterociterOperator's Avatar
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    Post Washington State Iinstallation Code

    Quote Originally Posted by seattleplumber View Post
    The whole point of the pad is to eliminate heat loss due to direct contact with the concrete floor. If the tank has feet that are more than just dimples in the sheet metal, a pad isn't necessary. Therefore, you wouldn't need to place a water heater with feet on a pad to begin with. That being said, if you try it the weight will sink the feet right through the pad. And if it's gas, it will melt the foam (seen it on an old style gas water heater).
    I was advised that the Washington State Installation code now requires the foam pad on electric water heater installs.
    Even with the new heaters there is significant heat loss from the bottom of the heater to the cold dense concrete floor below.
    Insulfoam makes the high-density "Insulpad Electric Water Heater Insulation" pad (7-32813-10043-0) $11.87 at Home Depot.
    I'd prefer to put in under the drip pan and get a little height for drainage, but I've never seen it installed that way.


    (It makes a poor frisbie)

  4. #34
    DIY Member charles2's Avatar
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    Got a link? I searched for this at homedepot.com and came up empty.

  5. #35
    DIY Junior Member InterociterOperator's Avatar
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    Insulpad Electric Water Heater Insulation Pad

    http://www.homedepot.com/h_d1/N-5yc1...1#.UEQAsaAf6PA

  6. #36
    DIY Member charles2's Avatar
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    I guess it didn't come up because it's only available in stores. 2" seems a little thin - I'd like to see about 12", but of course you could stack them.

  7. #37
    Forum Admin, Expert Plumber Terry's Avatar
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    2" is plenty. It's closed cell foam. I don't know if you ever sat on a small wafer of closed cell foam on snow before, but it colds the cold very well. When I sleep on snow, having just a thin pad to sleep on works wonders.

    I have seen drain pans installed over the 2" foam before. It's a good way to install them.


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